Technological Field
The present disclosure relates generally to the field of wireless communication. More particularly, in one exemplary aspect, the disclosure is directed to methods and apparatus for dynamically configuring search operations in a multi-mode device.
Description of Related Technology
Mobile wireless devices are becoming increasingly full-featured and complex, and accordingly must support multiple aspects of operation, including for example voice calls, data streaming, and various multimedia applications. Multi-network (also referred to as the multi-mode) wireless devices are often used to provide connectivity in mobile applications where uses may change their location (e.g., while traveling).
During so-called “roaming” access, a multi-mode device may attempt to switch between each of its available modes (networks), so as to identify a suitable cellular network for operation. For example, consider a multi-mode device having three modes: (i) CDMA2000 which is associated with the multi-mode device's home network, (ii) GSM, and (iii) WCDMA. During operation, the device will power up and attempts to scan for a CDMA2000 network (such as based on a Preferred Roaming List or PRL). CDMA2000 searches are based on detection of a so-called “pilot” signal. If the mobile device can identify the presence of the pilot signal, the mobile will proceed to acquire timing and phase alignment. Once the mobile device has aligned to the base station, it can synchronize fine timing, receive control information, and register to the network.
If no CDMA2000 networks are located, the device attempts to scan for any GSM networks, such as based on a Subscriber Identity Module (SIM) preference. During the GSM search, the mobile device searches for a beacon signal within the standard GSM frequency bands. If the beacon signal is found, then the device determines the timing by searching for a synchronization channel, which is transmitted according to a fixed schedule. If no GSM network is located, the device attempts to scan for any WCDMA networks based on a SIM preference. Once the mobile device has completed Primary Synchronization Sequence (PSS) and Secondary Synchronization Sequence (SSS) searches, the mobile device can decode the BCCH, and decode control information necessary to initiate network registration.
If no WCDMA network has been found, then the device repeats the foregoing process. This repeating or looping process is “fixed”, and does not change regardless of the mobile device's previous connection history. Furthermore, this process can waste a significant amount of power on modes which have less likelihood of success.
Accordingly, improved schemes for multi-mode device network searching are needed. Ideally, such schemes should reduce overall power consumption by intelligently allocating search time for each network technology, rather than looping through each available option until a wireless network is found.